/*
 * Copyright 2009 Original Author(s)
 * 
 * This file is part of Kommando
 * 
 * Kommando is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * Kommando is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with Kommando.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.kommando.script;

import java.util.HashMap;
import java.util.Map;

import javax.script.ScriptEngineFactory;

import org.kommando.core.action.Action;
import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceEvent;
import org.osgi.framework.ServiceListener;
import org.osgi.framework.ServiceRegistration;
import org.osgi.util.tracker.ServiceTracker;

/**
 * @author Peter De Bruycker
 */
public class Activator implements BundleActivator {

    private Map<String, ServiceRegistration> actionRegistrations = new HashMap<String, ServiceRegistration>();

    private ServiceTracker scriptEngineFactoryTracker;

    public void start(final BundleContext context) throws Exception {
        context.addServiceListener(new ServiceListener() {

            @Override
            public void serviceChanged(ServiceEvent event) {
                if (event.getType() == ServiceEvent.UNREGISTERING) {
                    unregisterRunAsScriptAction(context, (ScriptEngineFactory) context.getService(event
                            .getServiceReference()));
                }
                if (event.getType() == ServiceEvent.REGISTERED) {
                    registerRunAsScriptAction(context, (ScriptEngineFactory) context.getService(event
                            .getServiceReference()));
                }
            }
        });

        scriptEngineFactoryTracker = new ServiceTracker(context, ScriptEngineFactory.class.getName(), null);
        scriptEngineFactoryTracker.open();

        if (scriptEngineFactoryTracker.getServices() != null) {
            for (Object service : scriptEngineFactoryTracker.getServices()) {
                registerRunAsScriptAction(context, (ScriptEngineFactory) service);
            }
        }
    }

    protected void unregisterRunAsScriptAction(BundleContext context, ScriptEngineFactory scriptEngineFactory) {
        if (actionRegistrations.containsKey(scriptEngineFactory.getEngineName())) {
            actionRegistrations.remove(scriptEngineFactory.getEngineName()).unregister();
        }
    }

    protected void registerRunAsScriptAction(BundleContext context, ScriptEngineFactory scriptEngineFactory) {
        ServiceRegistration serviceRegistration = context.registerService(Action.class.getName(),
                new RunAsScriptAction(scriptEngineFactory.getScriptEngine()), null);
        actionRegistrations.put(scriptEngineFactory.getEngineName(), serviceRegistration);
    }

    public void stop(BundleContext context) throws Exception {
        scriptEngineFactoryTracker.close();
        actionRegistrations.clear();
    }

}
